Without saying more, I could leave the caption of this article as it is. However, doing so would be unfair to most Muslims who have been gravely misunderstood and misjudged due to the actions of a misguided few. It would also be unfair to people of other faiths who harbour misconceptions about Islam due to the actions of a misguided few, especially when viewed through the perspective of current events. 

It is important to define extremism in order to get a better understanding of what the issue in discussion is. 

Extremism is defined as a tendency or disposition to go to extremes or an instance of going to extremes, especially in political or religious matters. It could also be defined as any ideology (particularly in politics or religion), considered to be far outside the mainstream attitudes of a society or to violate common moral standards.

Let me clarify at this point that Islam does not allow extremism, not even in acts of worship especially where it would cause hardship to the worshipper or those around him/her. I'll provide some authorities from the Holy Qur'an to buttress this point;

"... If God had wanted, He could have been hard on you. God is Almighty, All-Wise "(Surah Al-Baqarah, Chapter 2:220).
Also, In  (Surah Al-A'raf, Chapter 7:42 ) Allah says:
"As for those who believe and do right actions, We impose on no soul any more than it can bear. They are the Companions of the Garden, remaining in it timelessly, for ever."

There are also prophetic narrations that condemn extremism. 

In Saheeh Bukhari, Volume 001, Book 002, Hadith Number 038 :
 The Prophet said, "Religion is very easy and whoever overburdens himself in his religion will not be able to continue in that way. So you should NOT BE EXTREMISTS, but try to be near to perfection and receive the good tidings that you will be rewarded; and gain strength by worshipping in the mornings, the nights" ( Narrated by Abu Huraira).

Also in Saheeh Bukhari, Volume 009, Book 092, Hadith Number 396:
 We were with 'Umar and he said, "We have been forbidden to undertake a difficult task beyond our capability (i.e. to exceed the religious limits e.g., to clean the inside of the eyes while doing ablution)" ( Narrated by Anas).

In one highly significant Hadith, Prophet Muhammad (SAW) is reported to have said, "Towards the latter times a people will come who have little knowledge, are deficient in intellect, will speak quoting the best of people, have thick beards, wearing shortened garments, have shaved heads, have good speech but foul actions, claiming to act upon the Book of God but have no relation to it, they recite the Quran but it doesn't pass their throats and they exit from Islam as an arrow exits from its bow."

Our judgments and opinions about people's character, disposition, race, religion and tribe are mostly based on the actions of individuals with similar backgrounds. Stereotypical you may call it? That is just the way it is. We're human beings and we may likely not be able to help it. With Islam, people erroneously judge Muslims based on the actions of extremist groups such as Al Qaeda, Hamas, Hezbollah, the Taliban and now the infamous Boko Haram. 

I would like to make use of some analogies to give a distinction between Islam the religion on one hand and Muslims through whom the religion is perceived or viewed. 

Imagine if you will, two individuals are given brand new cars to test drive for an hour. The first individual returns the test vehicle in the same pristine condition in which he received it; while the second individual returns his test vehicle and it is a total wreck. The side mirrors are hanging, the rear bumper is dented, there's a large gash across the side and there are weird sounds coming from the engine. Who would you blame for the wreck? The car that has no control over how it is driven or the driver who was in total control of the car? I guess the question itself yields the expected answer. Not convinced? Here's another analogy.

You're out to lunch and you decide to try out a new restaurant. Before you taste the food to decide if it is good enough to make you a regular patron or to recommend it to friends, a number of factors may come in to aid in your decision. These could be: Is there adequate and hassle free parking? Is it in a safe neighbourhood? Are the waiters/waitresses polite and professional? Did they take your order without errors? Did the food arrive late? Did it taste good?
Just as a car has no control over who drives it and how it is driven or a restaurant is adjudged based on the courtesy and professionalism of its staff, the same principle applies to Islam and other religions. The followers of any religion are the window through which others view the religion. In as much as you can find a lot of proof within the religion itself to show its true meaning and purpose, the actions of those who practice the religion may loom larger thus obscuring its actual intent. And in recent times the actions of some Muslims under the guise of doing ''Allah's work" have cast a dark shadow over the real message of Islam.

As far as doing "Allah's work" goes, Boko Haram are doing a bang up job. Their atrocities of recent have been increasingly shocking. So shocking in fact that Al Qaeda itself recently expressed outrage over some of Boko Haram's blood spilling campaign, especially the Chibok abductions. As a terrorist group, you know you've really crossed the line when another terrorist group with whom you have a lot in common cannot condone your actions. 

Every religion has at one time or another had extremists who took it upon themselves to go over and beyond prescribed limits as a show of devotion to their beliefs. David Koresh was a Christian extremist and leader of the Branch Davidians religious sect, believing himself to be its final prophet. A 1993 raid by the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives, and the subsequent siege by the FBI ended with the burning of the Branch Davidian ranch outside of Waco, Texas, in McLennan County. Koresh, 54 other adults, and 28 children were found dead after the fire. 
Jim Jones was another Christian extremist and head of The People's Temple and is best known for the mass suicide in November 1978 of 909 of its members in Jonestown, Guyana, and the murder of five individuals at a nearby airstrip, including Congressman Leo Ryan. Over 300 children were murdered at Jonestown, almost all of them by cyanide poisoning. 
Warren Steed Jeffs is another extremist who was charged and convicted of child sexual assault and incest. 
Judaism as well has had its own fair share of extremists. Eden Natan-Zada killed four Israeli Arab civilians on August 4, 2005. His actions were criticized by then prime minister Ariel Sharon, as "a reprehensible act by a bloodthirsty Jewish terrorist", and author Ami Pedhzer describes his motivations as religious. 
Baruch Goldstein, an American-born Israeli physician, perpetrated the 1994 Cave of the Patriarchs massacre in the city of Hebron, in which he shot and killed 29 Muslim worshippers inside the Ibrahimi Mosque (within the Cave of the Patriarchs), and wounded another 125 victims. Goldstein was killed by the survivors.

Despite these grave offences I wouldn't judge Christianity and Judaism as extremist religions. Neither would I support anyone to do so as the crimes in question are those of individuals and not the religion. Besides I've lived a better part of my life amongst Christians and some of my best friends are Christians who have stood by me in difficult and trying times. What sort of friend would I be if I considered them all to be extremists based on the crimes of a few Christian individuals?

Not to play the blame game and with all due respect to the media, sometimes certain captions used by the media play on the subconscious and give the wrong impression about Islam. Many times we see news headlines that focus more on the religion itself than on the individual crime. The usual headline the media uses is "Islamic Extremism". I feel the term "Extremist Muslim" best fits the description as it is not a quality in Islam that turns people violent, but the people themselves that are the problem. As Mohamed Ghilan said, it is not a problem within Islam per se; it is a problem with a particular mindset that very few Muslims fall into, which results in a very potently dangerous effect. 

I have on several occasions heard people pronounce fatwas to the effect that Boko Haram sect members are not Muslims due to the horrible trail of violence and destruction they leave in their wake. As Gimba Kakanda rightly said in his article titled "Of Conspiracy Theories and Denials", 'what the Boko Haram insurgents perpetrate is understandably un-islamic but they are Muslims. Disqualifying them as non-Muslims is not only a cheap escape from this maddening reality that begs for our honest confrontations but questions the authenticity of our own faith too.'
Members of Boko Haram are Muslims, at least outwardly. To excuse their actions by claiming they are not Muslims is not doing justice to the fact of the matter. Rather than say they are not Muslims, it would be best to accept the fact that they are Muslims but they are not being true to the Islamic faith. 

No doubt the actions of Boko Haram and other extremist groups are morally and religiously reprehensible. This fact cannot in any way be defended or denied. However, it is neither fair nor is it enough justification to place all Muslims into the same bloodstained cesspool. 

So, is Islam an extremist religion? NO. Are some Muslims extremists? Regrettably, YES. As a friend of mine Bello Saulawa said, "Islam is perfect, Muslims are not. Want to know about the religion, study the faith, not the people."